Lego Computer Case

Step 4: Basics of Computer Building - Fans?

Uff da, that's a lot of computer research but hopefully you've gotten a feel for the basics by now.  Now let's focus on what type of case fans to get.  Since the case will need to circulate lots of air, I suggest getting fans that have high cfm (cubic feet per minute of air pushed) ratings.  I think it's probably best to get the same model intake fan as exhaust fan to try to get neutral pressure inside the case (here are couple discussions on case pressure, more pressure stuff, and the king of all fans if you can afford it ze über-fan).  Depending on the motherboard you get and the number of fans you want, you might need a fan controller.  Make sure to look at the number of fans your motherboard will be able to control to know for sure!

Getting fan filters for the intake fans is probably a good idea too because you won't want dust to accumulate inside your case.

Comments

[baldmosher]

Practically, and keeping this explanation VERY simple, you want two bear in mind two key points. 1. more input than exhaust fans (creates positive internal pressure). 2. use as large fans as possible (150mm is ideal, 120mm is good enough). More detail to follow

[baldmosher]

More detail on 1. This is in order to drive dust out of the case (you then need to fit dust filters on your input fans only, and clean them periodically) and also drive heat out of the case (particularly as a Lego case will be purely air cooled - no conductive heat loss. Pay special attention to air flow inside the case, cabling, etc. and be prepared to use a temperature probe to check for hot spots. Don't forget your PSU will probably have a 120mm (or even 150mm) exhaust fan.

[baldmosher]

More detail on 2. The larger the fans, the slower they need to spin, and therefore the quieter they will be. For a general use PC sat on your desk, silence (or near silence) really is golden. Noise isn't a consideration for a server in a cupboard or the attic, but you'd be daft to build a Lego case for that purpose.

[greenyouse]

After running this computer for a couple days I've noticed that it may be slightly harder to get positive pressure in this case than in a conventional case.  The lego case isn't 100% airtight so some air leaks out, which creates a bit more negative pressure inside the case than normal.  Nothing too big, just thought it'd be helpful to mention.

BTW, negative pressure (pulling air out of the case) is kind of nice to have too because it cools the case more efficiently than positive pressure would.  Neutral pressure really is the best overall though because you'll get the cooling effects of the negative pressure and the dust blocking of positive pressure!  :D

[baldmosher]

You could always use PVA glue as cement? Strong enough to provide air tightness and some additional strength but still weak enough to snap off when dismantling.